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Is there a good source for estimating the per unit cost breakdown for a classic GA plane like the Cessna 172?
For instance, on a Cessna 172 what percent is spent on:

Raw materials
Labor actually manufacturing the plane
Testing the completed individual planes
R&D Making the plane (at this point, very little for the 172 I suspect
Certification testing
Insurance
Avionics
Anything I forgot...

Companies in all industries usually keep detailed cost information private so I think there's very little chance of getting a definite answer to this. But someone somewhere could have come up with a 'guesstimate' of course. It might be easier to get cost details for experimental - i.e. non-certified, homebuilt - aircraft but I'm not sure if that would be a useful enough answer?

If I say no there isn't, how do I prove it? You could always say "there must be one somewhere".

In light of this, I changed it to estimating in the title.

It's also worth noting that the used market for small planes is massive, far larger in fact than the market for new aircraft. A 2015 172 costs about $370k; you can buy a 1970 airframe with practically the same engine and airframe specs for $100k. That may, in fact, be a good place to start; an older airframe, assuming it's still airworthy, is going to be closer in cost to the sum of its parts than a brand new one. The difference is a combination of Cessna's overhead and true depreciation due to age and wear of the frame.

... And you'd be surprised how much R&D is still inherent in making the latest model years of 172; there are continuous incremental improvements made to everything from the airframe to the engines to the instruments and avionics.

@David Rosakm Aircraft Design part. VIII provides statistical methods to breakdown an aircraft cost.
You can find it probably at any Aerospace University Libraray.

I am confused.  You are asking about the "cost per unit that experiences a breakdown"?  In today's legal environment, that could be essentially unlimited (infinite).

If you want the exact cost or price you could in technicality buy all the materials used to produce the aircraft and then chart the costs and boom. (This is the long hard and inefficient way).

You can find an estimate in the Roskam book "Airplane Design Part VIII"
Which is partial on google books:
https://books.google.nl/books?id=GIHHFkd829cC&printsec=frontcover&dq=roskam+part+VIII&hl=en&sa=X&redir_esc=y#v=onepage&q=roskam%20part%20VIII&f=false
However, most Engineering Universities may have a copy of this series in their library. Most of the data you want to know, companies try their best to keep them private as it is information the competition would like to know.
In general most aircraft programs are based on an fixed set of sold units. If you know the cost of the individual units (aircraft) and the amount of units needed to sell to reach the break even point then you have a fairly good estimate over the program cost.


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Why were the specifications of the Pipistrel Panthera downgraded?
I'm curious if this was a failure of the simulations or a result of the engine swap they did at the last moment. Originally, they said they could cruise at 200kts @ 10g/h fully loaded. Now its down to 155kts.
http://www.panthera-aircraft.com/technical-data
EDIT:
Just wanted to add, for reference, a page which gave their original estimates.
http://www.pipistrel-usa.com/models/panthera.html
You will also notice at the top of the page for the first link where they reference the 200kts with 4 people for 1000nm.

it's not unusual for initial estimated specs to be off when it's actually tested (and the reason why tests are needed)

Yes, I just thought 47 knots was quite a mistake for a company with expertise in this area which is why I asked the question.

This sounds like an overly optimistic marketing department which wanted to make the aircraft look better. Engineering would allow to predict top speed within a few percent, so I would blame neither the simulations nor the engine swap.
The web page for the Panthera lists 155 kts only for the maximum range condition, which makes sense. Propeller aircraft need to fly rather slowly to maximize range. The cruise speed with maximum power is still close to 200 kts.
Please consider that the required engine power of propeller aircraft grows with the third power of flight speed. To give you the 200 kts top speed, the plane would need to run the engine with 215% of the power setting (and fuel flow) needed for 155 kts.
Once you know the installed power, you get reasonably good results just with the zero-lift drag and the propeller efficiency when you use this formula:
$$v = \left(\frac{2\cdot P\cdot \eta_{Prop}}{\rho\cdot F_{ref}\cdot c_{D0}}\right)^{1/3}$$
Nomenclature:
$v\:\:\:\:\:\:\:\:\:\:$ speed in [m/s]
$P\:\:\:\:\:\:\:\:\:\:$installed Power [W]
$\eta_{Prop}\:\:$ Propeller efficiency; use 0.85 if not known
$\rho\:\:\:\:\:\:\:\:\:$ density of air [kg/m³]
$F_{ref}\:\:\:\:$ Reference area for coefficients, usually wing area [m²]
$c_{D0}\:\:\:\:\:$ zero-lift drag coefficient
The zero-lift drag coefficient for small propeller airplanes is around 0.02 to 0.025 if they have a retractable gear. A very well designed airplane might come down to 0.016, but that is already pushing it. To fly fast, a high wing loading is essential, and then the influence of all non-lifting components on the total drag is rather high. A well-designed airfoil might achieve a $c_{D0}$ of 0.0035, but the whole airplane will be closer to 0.02.
Things get even worse when you aim for higher flight Mach numbers. The Dornier 328 turboprop was initially calculated for 320 kts cruise speed, but Marketing felt the need to claim 340 kts. The difference does not sound substantial, but all engineers thought they must be crazy over in Marketing. In the end, the Do-328  needed 30% more installed power to fulfill the promises made by the (rather irresponsible) Marketing department. The increased engine power indirectly caused an accident in flight test when a propeller (with an unchanged, but now too weak propeller mount) broke off in sideslip and cut through 1/3 of the fuselage. Luckily, the aircraft landed without further incident after that ...
(Disclaimer: This is from the back of my head, and I think I remember the facts and figures correctly. If any of you know more, please edit the last paragraph!)

Thanks for the detailed answer! I actually just started a Masters in Aerospace Engineering so it was particular interesting. I would agree with the marketing angle completely, but Pipistrel does have an amazing history when it comes to outstanding aerodynamics, and have multiple NASA awards to show for it. The Virus SW now cruses at almost 150knots @ 75% on a 100HP engine. That being said, I may leave this question open a bit longer just to see if anyone has actually talked to the company about this issue. Thanks again!

@David: The specs look realistic, and I did not notice the Panthera before, so I do not know what their initial claims were. I guess they were intentionally vague to let anyone confuse maximum cruise speed and optimum cruise speed.

I just added a page with the original speed estimates up top. Here it is again for reference: http://www.pipistrel-usa.com/models/panthera.html . As you can see, their range was changed to 1000nm @ 200kts to 1000nm @155kts, which is quite a dramatic shift.

@David: Thanks for the link! Yes, this page makes some incredible claims, and it suggests that >1000 NM range is achievable with 202 kts cruise speed. The 202 kts will need more engine power than 210 hp, however, and then those 10 gal/h are not right anymore. BTW, I find the claims for the fully electric plane even more incredible.

Are you talking about the electric Panthera, or this:
http://www.pipistrel.si/news/wattsup-the-new-2seat-electric-trainer-took-its-maiden-fligh
I'm very excited to see these planes starting to hit the market, but its going to be another 5 years or so until they have the range to make sense. This one looks like a battery version of the Virus SW.

@David: Yes, I was talking about the electric Panthera. A glider-like configuration is much better for electric propulsion, so the Taurus and WATTsUP electric airplanes are the right way to go. Given the recent advances in battery performance, even 5 years will make some, but not much of a difference.

May I suggest "cube root"  instead of "third power"?

@yankeekilo: O boy, what a stupid mistake! Thank you very much for the suggestion!!! I have rephrased it to what I had initially in mind.

Peter, not to worry - the equation says it all anyway :D ... and thank you for the excellent answer and the anecdote!

They could get to their target if they pressurised the cabin, chose a turbo charged engine, and flew at FL25. Current max cruise speed is achieved at FL12.
In fact, if they went with the IO540 with 350hp they could have the record for fastest piston single, I estimate 262KTAS at FL25. Probably worried about heat dissipation. Also, it isn't what they want to do.
The SMA 400hp diesel would be interesting in this plane, despite weighing 600lbs.

welcome to aviation.se. I'm sorry, but while interesting, I do not see how your post is answering the question. could you rephrase it?

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Is this takeoff of a 767 in bad weather conditions a normal procedure?
In this video, a 767 takes off in bad weather conditions. The comments of the video aren't very professional, so I ask here:

Is this a legitimate takeoff?
Some comments say that this was a close takeoff. Some comments do point out that on rotate, you can see the end of the strip of the lefter runway. Was it airborne before?

Holy cow... Look at the spoiler deflection during the takeoff run. I'm guessing that wasn't helping their takeoff distance.

@reirab You're right but seems that spoiler deflection is normal on full Ailerons to the Right.
http://www.airliners.net/aviation-forums/tech_ops/read.main/303976/

Yeah, I assumed that was the reason for it, but, still, that's a lot of spoiler deflection for a takeoff run.

The strips that you can see underneath the aircraft during the rotation are touchdown zone markings: http://en.wikipedia.org/wiki/Runway#Runway_markings

Take-off within the crosswind limits is a normal procedure. From the video it's hard to tell what the crosswind was in this particular situation, so it is impossible to tell about the legitimacy of this take-off.
Rotation seems to be on the 1000ft marker, i.e. 1000 ft from the runway threshold. But in case of a displaced threshold the take-off distance available may be more than 1000ft from that point. It was airborne before the end of the runway.

Given the aileron/spoiler deflection, it certainly seems that the crosswind was rather high, but you're right that there's no way really to tell exactly what they were.

Without having a better understanding of the actual crosswind there's no way to say whether that one was out of limits. If I had to guess I'd say it was close. I fly light aircraft, not commercial jets but as far as I know takeoff in a heavy crosswind is similar - you keep aileron into the wind, and a bit of forward pressure on the stick to make sure your wheels have good contact to the ground. During the roll you build up a bit of extra speed so when you are ready to rotate you get well off the ground quickly so you get some ground clearance, and also have better control authority. It looks to me that's what these pilots did.
Given the conditions it was never going to be a comfortable ride, I see nothing wrong with the take-off.

Assuming everything was within its limits since we can't prove otherwise and therefore a legitimate take-off, it's the captain's call whether to take-off or not.
Nevertheless, judging by the video, the precipitation seems far too severe to consider this take-off completely safe. Also, the crosswind might have been quite strong considering the open spoilers (also called airbrakes) caused by full left aileron being applied to compensate for the crosswind, which ultimately increases the take-off distance.
Furthermore, if it was a stormy cumulonimbus cloud, the take-off could have been delayed by half an hour, and the meteorologic conditions would have been much better in terms of precipitation (and it would avoid scaring all the passengers).
From my point of view the main problem with such take-off would be in case of a take-off emergency (like an engine flame out due to the intensive water ingestion) before V1, forcing the pilots to brake, risking a runway overrun due to hydroplaning.
They made it, but I don't think it was the smartest decision!

"risking a runway overrun due to hydroplaning" - runway surface conditions are factored in as part of the V1 speed. The whole point of calculating V1 is to determine the speed at which the aircraft cannot be safely stopped on the remaining runway given the current weather and surface conditions.

@SteveKuo True, V1 calculation takes into account runway conditions (and should give a good safety margin) but a significant amount of time can pass between V1 calculation and the actual take off. Such amount of time could be enough for meteorological conditions to deteriorate. So in the end it comes down to the pilots experience and sometimes that's just not enough... Take a look on point 5.5.1 from this paper of dutch aerospace laboratory.

Sorry, forgot the link. http://reports.nlr.nl:8080/xmlui/bitstream/handle/10921/758/TP-2001-216.pdf?sequence=1

It looks like it was raining (a lot) with a pretty good crosswind. They probably loaded extra fuel for the weather and decided to rotate after Vr instead of exactly at Vr, thus using more runway. Wiggling the controls around didn't help the takeoff roll but it did keep the plane straight - usually a good thing.
As a passenger this would not have bothered me at all. Some years ago I was departing Hong Kong on Northwest, right in the middle of a typhoon. We sat at the threshold for 20-30 minutes, then the engines went to full power and we got out of there. The FA across from me said the flight crew told them to buckle in and stay seated for 20 minutes after takeoff, and she'd never heard that in her career. So obviously the pilot felt it was going to be a rough ride but he also felt it would not be a problem.
Landing back at the airport in the video would have been quite exciting, possibly requiring the Force in addition to redundant Cat IIIb autoland. But there's no requirement that you return to your departure airport if you have a problem - if there's another one 10 minutes away with better weather you go there instead.

$V_1$ is the speed after which you are committed to take off, but not the speed at which you can actually take-off. Rotation speed is $V_r$.

"[flight attendants would] stay seated for 20 minutes" - it's not that uncommon; I've been on flights like that a few time. The most recent was yesterday, flying from Chicago to New York; the pilot announced before takeoff that he had just come in from New York, and things were pretty choppy over the Great Lakes, so beverage service would be delayed because the flight attendants would be buckled in for about the first 40 minutes of the flight.

Interesting. Looks like my FA never worked the northeast routes then. If I recall, she preferred long-haul.

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How can I find my grandmother's OLD instrument rating documentation?
This is my grandmother, Nathalie Myrtle Brown:

The big-eared kid she's posing with is my dad.
She has a claim to fame in that she was the first female instrument-rated pilot in the state of Iowa, a fact that figures prominently in her obituary

In the 1960s [...] Nathalie and Walt took flying lessons and became licensed pilots. Natalie, the first woman pilot in the state of Iowa to hold an instrument rating, enjoyed flying their planes back and forth between Iowa and Colorado.

I distinctly remember, though, my mother telling me that Nana was the first female instrument-rated pilot west of the Mississippi River.
That memory is the only basis I have for thinking the achievement might have been more than 'first in Iowa'. Unfortunately, Mom died a few years ago and no one else in the family remembers anything bigger than the state of Iowa for the claim.
So, I'm curious. How can I read her pilot certifications from the 60s, possibly earlier?
The sub-question here has been answered to my satisfaction. The "west of the Mississippi" memory is nothing.

next day: I found a newspaper clipping from The Carroll Daily Times Herald, 19 June 1965, showing that she landed in Carroll, Iowa that week. Apparently all landings at the Carroll airfield made the paper. Amusing.

Here's an undated photo from the website of my cousin, Maribeth:

Perhaps there's a clue in the picture to date the plane? I have no idea which came first, the Piper Cherokee or the Cessna. @reirab points out in comments that people without an aviation background often call small planes Cessnas and the fact that Cessna is misspelled on the picture certainly supports the idea that it was done by someone without said aviation background. This could be the Piper Cherokee?

I was totally winging it (haha) when I picked tags. Please edit as appropriate.

Welcome to aviation @Jolenealaska! It's a long way from Cooking.SE! I'm assuming you looked through personal effects? Can you give us an idea on the year she got her IR? That will give us a better idea of how to answer.

Hmm... Especially the claim about being the first instrument-rated pilot West of the Mississippi in the late 1960s sounds extremely unlikely to me, though I'm not intimately familiar with the history of the instrument rating. By 1968, 707s and DC-8s had been flying for a whole decade and were regularly flying between continents. The Boeing 747 first flew only about 3 months after your grandmother first received a pilot certificate. These were not the early days of aviation (those were more like 60 years earlier.)

Amelia Earhart co-owned a pilot school that taught instrument flying in Burbank in 1935. And I doubt she was the first to teach it - let alone be rated for it - West of the Mississippi.

Any chance you could locate her logbook(s)? Those would be a treasure!

@reirab I think you're absolutely right that the "west of the Mississippi" claim is extremely unlikely. Both of your comments make it seem pretty obvious. I'm 99.99% solid on the Iowa one, though. Like often happens on SE, now that I've asked, I really want to know!

@FredLarson They would to me anyway. Not keeping memorabilia is a trait that unfortunately runs through all generations of my family.

A charming story.  Yay Nathalie!

@jolenealaska: Yes, a treasure to you and your family is what I meant. Probably little monetary value, but priceless!

I think the pictured aircraft may actually be the referenced Cherokee. A lot of people who aren't very familiar with general aviation just call any light, single-engine plane a 'Cessna,' even if it isn't really a Cessna. Most Cessna light aircraft are high-wing designs, whereas the pictured one is low-wing (and, at least from what I can see of it, it looks like a Cherokee to me.)

The FAA has an airmen inquiry search portal. I put Nathalie Brown and came up with Nathalie Myrtle Brown with the following details:

Certificate: PRIVATE PILOT   Date of Issue: 11/25/1968
Ratings: PRIVATE PILOT
AIRPLANE SINGLE ENGINE LAND
AIRPLANE MULTIENGINE LAND
INSTRUMENT AIRPLANE

As @FredLarson points out in comments the date supplied seems to be the last change to their database, i.e. address, name or addition of rating, so that means she must have gotten all of her certificates at or before the 25th of November, 1968.
This is a start, but it doesn't give you real dates. If the FAA has that much information they should have a lot more, to get details you should contact the airmen certification branch. I'm not sure what hoops you have to go through, maybe prove you are family, etc.
There is a big database of pilots from the FAA search portal, but it is not complete - your grandmother wasn't in it for example, and there's no dates of ratings anyway. Maybe the FAA can get you access to a better airman database with more of those records, it's possible they simply don't exist anymore though, you'd have to ask.
If she has personal effects left then her pilots certificate or other details may be there, certificates used to be paper, probably folded up. Really useful would be her logbook, which would be a record of every flight she made, there would be endorsements in these which would be useful in learning when she achieved her ratings.

Myrtle is her middle name (now that I'm reminded of it). Very cool GdD! Thank you! Very helpful.

Glad I could help a bit @Jolenealaska, I've added more details which may be useful, it depends how much digging you want to do.

As a non-aviator, I don't understand this part: "This is a start, but it doesn't give you real dates." I can clearly see a date in those details, what's missing?

@Jolenealaska: You may not know this, but Myrtle ~= Esther via a different set of translations and transliterations.

Are you sure the "Date of Issue" means when she originally got her private pilot certificate? Just looking at my pilot certificate, it has a "Date of Issue" that matches when I got the latest certificate due to an address change, which is nearly 20 years after I got my original private pilot certificate and about 15 years after I got my instrument rating.

Just followed the link and looked up my own information and sure enough, it give the same date that is on my certificate -- 20 years after I became a private pilot. So I'd say she got her instrument rating no later than 1968.

I just found a newspaper clipping that has her landing in Carroll, Iowa in June of 1965, so your conclusion that her license was prior to 1968 is correct.

@FredLarson That makes a lot more sense. It seemed nearly unbelievable that no female pilot had received an instrument rating in the entire state of Iowa prior to 1968.

You may wish to contact FAA Airmen Records in OKC.  They will likely have the record.  They are retained indefinitely.  It will likely have been pruned from the current database, since she does not hold a current medical.
The Date of Issue of certificates is not always the original date of issuance.  It is merely the date the FAA made a record update which constitutes a change of issuance for their record keeping.  A common example is a certificate number change from a SSN to a pilot ID assigned by the FAA.  It used to be that name changes caused a new Date of Issue. Also revoked licenses and their subsequent re-issuance will trigger a new Date of Issue.
As for verifying the other claims, such as whether she was the first instrument pilot in a region, the FAA has not retained that data in the Airmen Registry, and newspaper articles or other sources may be a better source.

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How does the rotor blade material affect aircraft performance?
Helicopter rotor blades in newer helicopter designs are made from composite materials. This results in improved performance. Is this simply because they are lighter or is there another reason behind that?
For example, for the new CH-53K the blades are made from titanium fiberglass composite. The use composite rotor blades results in better "hot+high performance".

How can that be? Isn't performance simply weight/lift ratio?

@mins what do you mean?

I was referring to your last sentence: "Isn't performance simply weight/lift ratio?". Without changing the weight, only the material, performance is affected due to different characteristics of the materials, which lead to different modes of vibration or deformation of the blade.

Have you got a reference for the quote on better "hot+high performance"?

wikipedia has two references in the design section. Unfortunately, both are no longer valid. I also read it in a newspaper article about the helicopter but also without references.

The Hot and High conditions refer to the worst atmospherical conditions for the performance of an aero-engine in general. This is due to two phenomena:

HOT: When the outside temperature is high, on one hand, the pressure decreases (due to the decrease of density of the air) and thus the mass flow rate and thus the power decreases (the power is proportional to the mass flow rate). On the other hand, the ratio TIT/Ta (Turbine Inlet Temperature of the atmospheric temperature) will also decrease. This will lead to a reduction of P and to a reduction of the effective efficiency (the power and the effective efficiency are proportional to this ratio), the result is also an increase off the specific fuel consumption (SFC).
HIGH: At high altitude, the pressure decreases and thus the density and the mass flow rate. The power will then decrease (as above for the HIGH condition) and the SFC will increase.

What are your options then ? Well, you can put a more powerful engine to compensate for these conditions but you will most probably increase the weight and the fuel consumption a lot (and the cost for sure). You can use the same engine but at a higher regime, but again, you will consume a lot which is not ideal. But there is another solution: you can make your helicopter or aircraft lighter. This whey, you need less power. And that's what brings composites in general; an important gain of weight.
Hope it helps !


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What is this pipe on the tail of this helicopter?
In this picture of a CH-53 you can see a pipe or rail on the tail section of the aircraft. What is that?

This device is the antenna for the HF transceiver.

Source
The antenna is the rigid wire running along the top of the fuselage and ending near the window, supported by insulators at regular intervals to move it away from the metallic fuselage for better efficiency.
HF antennas used on helicopters are often loop ("towel bar") and inverted-L antenna (the one you have found).
Length: RF signals travel in a wire and bounce at its extremities. This is also valid when this wire is used as an antenna. In that case the wire takes the name of radiator. The antenna radiates a stronger electromagnetic field when the direct signal and the bounced signal combine in an additive way in the radiator (resonance). This efficiency gain is also valid when working in reception.
RF signals travel in a wire at about 66 to 95% of the speed of light (velocity factor). To make the resonance happen the length of the radiator must be a multiple of the wavelength, or a carefully selected fraction of it, e.g. $\small 1/4$, $\small 1/2$, $\small 5/8$, ... (more) corrected by the velocity factor. The radiator size is therefore proportional to the wavelength used, and the radiator used in HF is longer than the radiator used in VHF.
Diameter: HF band also usually requires higher power (and higher voltage) for the long distance communications it is aimed to.
The result of both requirements is an HF antenna radiator should be longer and should have a larger diameter than for a higher frequency. This leads to designs similar to CH-53 antenna.
In practical the antenna won't resonate for all aviation HF frequencies which are spread over a large range (100 m to 10 m), shorter wavelengths will be privileged.
Some examples:

Source. Notice the smaller VOR/LOC antenna

Source

Source
See also: Why did some Caravelles have a very long dorsal fin?


text:
What is aeroelastic deformation?
Some answers on this site, such as this one, refer to something called aeroelastic deformation.
What is it and how does it affect aircraft construction? Are there any famous lessons learned on this topic as far as aircraft construction goes?

Aeroelasticity is the elastic deformation of a structure caused by aerodynamic forces. An example is the flexing of a wing. The change of the shape of the structure has in turn an effect on the aerodynamics.
Aeroelastic effects can be static, such as the upward deflection of a wing under the influence of lift, or dynamic.
In the static case, the aerodynamic for cause the structure to deform. If the structure is very flexible this can cause a stability problem: the deformation causes an increases of the aerodynamic load, that will in turn increases the deformation until the structure fail.
In dynamic cases there is an interaction between the aerodynamic forces, the inertial forces and the deformation of the structure. Usually the dynamic behaviour is transient and damped.
When the dynamic behaviour is undamped (the aerodynamic forces add more energy than is dissipated in the transforming structure) an increasing vibration will occur. This is called flutter. Flutter is unwanted the because the resulting severe vibrations can cause structural damage.
Here is an example of flutter on a small aeroplane:

it's only flutter if the interaction is undamped, sustained.

Maybe add that the static case is actually a stability problem: If the structure is too flexible, the deformation increases the load which in turn increases the deformation until the structure fails.

Here's a good example of flutter. It looks like it gets close to becoming completely unstable and failing. https://m.youtube.com/watch?v=iTFZNrTYp3k. In 1959 a Lockheed Electra crashed due to flutter, killing all 34 passengers. https://en.m.wikipedia.org/wiki/Braniff_Flight_542

The earliest form of aerolastic deformation gave rise to the famous control reversal of the aircraft trying to break the 'sound barrier'.
At high airspeeds, moving the elevator up created such a large force on the aft end of the tailplane ('stabiliser') that it twisted (which it wasn't designed/expected to do). The twisting pushed the aft end of the tailplane down, which gave the tailplane a net 'upwards' shape, and so the aircraft pitched down when the elevator was moved to give a pitch up.
A similar problem happened in roll, the aileron forcing the wing to twist in torsion, and thus the aileron acted as a tab with the wing itself acting as the aileron.
Measures now are...
* more metal in the structure
* moving stabiliser
* not using tip-mounted ailerons at high speed.


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Why does the Las Vegas Airport have three control towers?
Why does the Las Vegas Airport have three control towers? I just noticed, and I find it a little weird. There should only be one... Does anybody know details on how this came about? And how they work like that?

EDIT: Not a duplicate, the question is specific to Las Vegas Airport, the other question is about another airport.

From the Airport Diagram, I only see a single control tower, located just west of Terminal 3.  Where do you think the others are?  Please provide references.

Possible duplicate of How does having multiple ATC towers affect airport operations?

Yes, I noticed that too. Strange, isn't it?

I've added an image from Google Earth that shows the three towers that I believe you're referring to.

Relevant:  https://www.reviewjournal.com/local/local-las-vegas/old-mccarran-airport-tower-meets-a-1-99m-demise/
Old tower is scheduled to be demolished.  The other "tower" is likely ramp/ground control.

@GregHewgill This question is about the Las Vegas Airport. The other question is about Schiphol airport. Please also note, that Las Vegas has three towers, which is very unusual, Schiphol has two. Please read the question more carefully before flagging a question. This causes at least another edit for me for an absolutely valid question, that I already had research before posting, and that already required three edits in one hour...

@mike Last time I counted (it was today) Schiphol had five towers.

@DeltaLima Really? Where are they all? I'm only aware of "the tower" and the one by the polderbaan...

There are two operational towers at Schiphol (the main tower and tower west at the polderbaan). Then the former control tower next to the main tower and the tower at gate D. Finally the very old tower (1952) at Schiphol east which now is a restaurant/flight simulator facility, across the road from the ATC centre building.

There are three tower structures, but only one is the control tower

One of those is the old tower, built in 1983, and scheduled for demolition.
(in the bottom left of the picture)
The location and height of the old tower created blind spots, which were covered by the much shorter ground control tower attached to the D Gates. (upper right of the picture)
The new tower is in a better location, and tall enough that it doesn't have blind spots.  I couldn't find a reference to if the D-Gate mini-tower will continue, or be demolished.

How do you know that?

https://www.reviewjournal.com/local/local-las-vegas/old-mccarran-airport-tower-meets-a-1-99m-demise/

airports which have existed for many years often have a succession of control towers which were built in each revision of the airport, and in some cases the older ones are allowed to stand. I look for them each time I land at an unfamiliar airport- the more towers, the older the airport, and the more history there is in front of me.

The mini tower is the East Ramp Control tower, used to park planes at assigned gates. There is another Ramp Control Tower situated on the south end of the terminal 1 garage that monitors the west airfield.

Can you expand on that and provide some pictures please?

Previous commenters are correct that old towers can stay around well after a new one is put up. Look at IAD. I'd also add that sometimes there are ramp towers at airports and they can look like regular air traffic control towers.

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text:
Have any helicopter or gyro copter rotors driven by tip propellers been built
I remember the 4 bladed X wing and a two bladed tip jet rotors that were driven by compressed air, in the 1990s.  I believe there was a early 1900 rotor that was driven by propellers at the tips.  And, I think was there a human powered gyro copter that had propellers at the tip.  Does anyone have any references to tip propeller driven rotors?
My real question is what are the flight conditions where tip propeller driven is beneficial.  At first glance, the power required to drive the propellers is in addition to the power required to drive the rotor, so there wouldn't be any flight conditions where the tip propeller drive is better than shaft drive or tip jet drive or tip compressed air drive.  It's possible that for light thrust or small induced main rotor power, that a tip propeller could require less power.

What do you mean by a 'tip jet propeller'? Surely it's one or the other?

The concept is a two bladed rotor driven by two two-bladed propellers at the tips of the rotor.  So the rotor has low twist, similar to a helicopter rotor.  And the small propellers have twist like an airplane propeller.

Look at this concept.  https://hackaday.com/2022/08/08/large-tip-driven-copter-turns-very-slowly/

You should edit your question to clarify what you're after. You're currently referring to "tip jet propellers". You're getting tip jets because they existed. If you want tip propellers you should make that clear.

You right, let me change the wording to emphasize tip propeller drive.

You're correct that the phrase tip jet propeller was incorrect.  I meant tip propeller.

You are describing a propeller-driven propeller. This idea pops up from time to time, but always encounters the same fundamental problems, as follows.
First of all, the gyroscopic stresses on the propeller at the tip of the blade where the blade is rotating at ~800 RPM and the propeller is going ~2500 RPM are enormous, and would require an enormously strong main hub assembly.
Second, a main rotor going ~800 RPM has its tips approaching the speed of sound, as are the tips of an ordinary prop going ~2500 RPM. The combined air velocity at the tips of the propeller will be supersonic even when the helicopter is stationary. Any forward velocity then gets vector-added to the other velocity components and the problem gets worse. Cyclic stresses on the roots of the propeller blades will have a very strong once-per-revolution component which will not be good.
Finally, the windmilling drag of a dead tip propeller would probably make autorotation of the main rotor impossible.

I'm looking for tip propeller driven rotor design.

OK, got it.  -NN

The original question was misleading.  I've modified it to emphasize tip propeller driven.

I'd add also the similar problem of the jet version, that is, making the power (electrical or mechanical) reliably reach the tips of the main rotor.

Fairey Aviation built the Jet Gyrodyne(first  flight 1954), as a precursor to the Rotodyne(first flight 1957). The Rotodyne was intended for civil and military applications, but attracted no orders, in part due to the noise from the tip jets.
The Jet Gyrodyne was originally intended to be scrapped, but survived and can be seen today at The Museum of Berkshire Avaiation
Some parts of the Rotodyne survive (but not a complete airframe) and can be seen at The Helicopter Museum
Jet Gyrodyne:

Wikipedia
Fairey Rotodyne

Wikipedia

The Rotodyne was said (by a UK test pilot) to 'stop conversations from a mile away'.

I'm not looking for tip jet rotor, looking for tip propeller rotor.  Different specific thrust range.


text:
Under what conditions can the maximum angle of climb be achieved for jet and propeller aircraft?
I know that the maximum angle of climb is reached at maximum specific excess thrust (S.E.T.) for jet airplanes, or minimum drag or maximum $\frac{L}{D}$.
Is this true, and if yes, is this valid also for propeller airplanes, or is $\gamma_{max}$ reached at another condition for props?

What you say is true only for turbojets and aircraft with fixed-pitch propellers. Generally, all optimum points for variable-pitch propeller driven aircraft are at lower speeds than those of jet aircraft. The reason is the variation of thrust with speed: For propellers, thrust is inverse to speed, while it is roughly constant over speed for turbojet aircraft in the subsonic speed range.
Specifically, the optimum angle of climb condition can be expressed as $$\frac{\delta \gamma}{\delta c_L} = 0$$
If we assume a quadratic polar, constant propeller efficiency over speed (which means a variable-pitch propeller) and an expression for thrust which lets us model an exponential variation of thrust over speed ($T = T_0·v^{n_v}$), we can write this condition as $$\frac{\delta \gamma}{\delta c_L} = -\frac{n_v}{2}·c_L^{-\frac{n_v}{2}-1}·\frac{T_0·(m·g)^{\frac{n_v}{2}-1}}{\left(\frac{\rho}{2}·S_{ref}\right)^{\frac{n_v}{2}}}+\frac{c_{D0}}{c_L^2}-\frac{1}{\pi·AR·\epsilon}$$
The general solution is $$c_{L_{{\gamma_{max}}}} = -\frac{n_v}{4}·\frac{T·\pi·AR·\epsilon}{m·g}+\sqrt{\frac{n_v^2}{16}·\left(\frac{T·\pi·AR·\epsilon}{m·g}\right)^2+c_{D0}·\pi·AR·\epsilon}$$
For jets and fixed-pitch propeller aircraft ($n_v = 0$) the solution is quite simple, because the thrust terms are proportional to the thrust coefficient $n_v$ and disappear: $$c_{L_{{\gamma_{max}}}} = \sqrt{c_{D0}·\pi·AR·\epsilon}$$
For turbofan and variable-pitch propeller aircraft, we have less luck and get a much longer formula. This is the one for propellers ($n_v = -1$):
$$c_{L_{{\gamma_{max}}}} = \frac{T·\pi·AR·\epsilon}{4·m·g}+\sqrt{\left(\frac{T·\pi·AR·\epsilon}{4·m·g}\right)^2+c_{D0}·\pi·AR·\epsilon}$$
To arrive from here at a flight speed, I recommend to look up the speed in a polar. Solving this analytically will get messy. Below I have plotted a generic climb speed over air speed chart for different thrust loadings of a typical turbofan. The blue lines show thrust (right Y-axis) and the green lines the resulting climb speed. The two black lines show how the optimum flight speed for best climb speed and best climb angle (steepest climb) vary over thrust loadings. They are easy to find graphically: Pick the tops of the green curves for best climb and the steepest tangent from the origin of the coordinate system to the green lines for best climb angle. Note that they cross when moving from positive to negative climb speeds. With a propeller, the results will look similar, however, the best climb speed line would be vertical. This will collect all optima at the low speed range of the plot - using a turbofan makes the effects easier to see because the optima are spread out more.

Climb optima for different thrust loadings (own work)
The optimum climb speed (which is proportional to $\frac{1}{c_L^2}$) varies inversely with the square of the thrust loading ($\frac{T_{ref}}{m·g}$)² of the aircraft. With lots of excess thrust, the optimum is limited by the stall speed (the black line bends into a vertical trend), while with no excess thrust both optimum speeds $v_x$ and $v_y$ converge. This makes sense: If thrust is just sufficient to keep the airplane from descending at one speed, this speed will both give the best flight path angle and the best vertical speed (unfortunately, both will be 0 at this point). It also helps to reduce induced drag, so aircraft with a high aspect ratio wing will climb steepest at a higher lift coefficient (= lower speed).
The steepest climb optimum looks a little more compact if we use the induced drag coefficient directly: $$c_{L_{\gamma_{max}}} = \frac{2·m·g·(c_{D0}-c_{Di})}{T}$$
but since the lift coefficient is hidden again in the induced drag term, and so sits on both sides of the equation, it is much harder to draw conclusions from this version.
Nomenclature:
$c_L \:\:\:$ lift coefficient
$n_v \:\:\:$  thrust exponent, as in $T \sim v^{n_v} $
$T \:\:\:\:$  thrust
$m \:\:\:\:$  mass
$g \:\:\:\:\:$  gravitational acceleration
$\pi \:\:\:\:\:$  3.14159$\dots$
$AR \:\:$  aspect ratio of the wing
$\epsilon \:\:\:\:\:$  the wing's Oswald factor
$c_{D0} \:$  zero-lift drag coefficient
$c_{Di} \:\:$  induced drag coefficient

The maximum angle of climb for all aircraft is achieved when the specific excess thrust available is maximum.
$sin \ \gamma_{max} \ = \frac{(T-D)_{max}}{W}$
However, the thrust varies differently with speed in case of propeller and jet engines.

Source: code7700.com
For turbojet aircraft, the thrust is approximately constant with speed. So, $(T-D)_{max}$ (and maximum angle of climb) occurs are $D_{min}$. This velocity is the $V_{min_{T_{R}}}$, the velocity of minimum thrust (drag) required and also the velocity for maximum angle of climb, $V_{\gamma_{max}}$. i.e. for jet aircraft, $V_{min_{T_{R}}}$ = $V_{\gamma_{max}}$.
In case of propeller aircraft, the thrust varies with speed. In general, thrust decreases with speed. As a result, the maximum excess thrust (i.e. the maximum SET) does not occur at the speed of minimum drag, but usually before it. As a result, for propeller aircraft, $V_{\gamma_{max}}$ < $V_{min_{T_{R}}}$.
The condition is the same (max. excess thrust), but the speeds are different.


text:
How does a single engine tail wheel landing gear airplane turn when it is on the ground?
Say Cessna 140 as in this video, look like no additional device to make it turnable when it on the ground. It is a single engine and a tail wheel landing gear. Then, how does it turn?

The rudder cable circuit is also connected to the steerable tailwheel through springs that provide a compliant connection.  When you push a pedal it also creates a turn in that direction on the ground.
However the arrangement is unstable in the rolling plane.  The main traction elements, the two front wheels, are ahead of the center of mass so the thing wants to switch ends, like pushing a shopping cart backwards.  So there is no rolling self-aligning tendency like with a tri-gear and you have to actively provide "artificial stability" with your feet.
That, plus the kind of laggy response when the little wheel in the back is turned, with a springy connection, means there is usually a little foot dance going on while you are rolling.  When necessary, you use differential braking to help things along if a steering input (a stab on the rudder) isn't having the effect you want.
Once you are rolling above about 30 mph, the rudder itself starts to provide most of your steering control.
Taildraggers take quite a bit more attention and skill to control while rolling, which gives them a bit of cachet that trigears don't, among pilots that are into that sort of thing (like me).
How it all works:  In the exploded image below, Item 6, the steering horn, is connected to the rudder itself and it turns Item 26, the steering fork (or half fork in this case), which has the wheel on it (the springs are to provide some give to the connection to avoid over stressing things when the wheel touches down unaligned with the surface).
The interconnection between 6 and 26 has various parts that make it work a bit like a breakout clutch; 6 can turn 26, but if 26 is turned by an outside force above a certain point, its connection to 6 releases and it can caster or swivel freely until they line up again and re-engage.
So when you are rolling and work the pedals, the pedals/rudder turn the steering horn (Item 6) and it turns the fork (Item 26) with the tire as if they were a single unit and the airplane turns.  If you are nearly stopped and want to spin around to park, you lock one of the brakes and this puts so much side load on the tailwheel it breaks the fork out of its connection to the steering horn and it's free to swivel.
Later when you are rolling straight and the steering horn and tailwheel are lined up, they lock together again and you have steering control back. The internal breakout mechanism has to be set up so the breakout force required isn't too high (hard to make swivel) or too low (starts swiveling freely when you don't want it to).  You don't want it to start swiveling while you are still rolling at speed and using it for steering, or, like shoving a shopping cart backwards, around you go! (It's called a ground loop)
This is a "steerable/free castering" tailwheel and variations of this type of system are used on probably 95% of GA tailwheel airplanes out there.  When steering with this system, brake can be used as required to assist with steering because the steering authority is limited compared to a nosewheel but you generally only  apply brakes if you really have to, to avoid wearing the brakes out (the springy nosewheel connection in a Cessna 150 is similar).

Do you know the rough percentage of GA taildraggers that have a steerable tail wheel?  I know some do, but was under the impression that a majority castor freely.

I have a friend with a Tiger Moth built in the early 40s with a free castering tailwheel that does't lock or anything.  It's a challenge.  Other than that you will see two configurations in virtually all cases; steerable or locking/castering.  On some larger taildraggers the tail wheel locks straight for takeoff and landing and can be unlocked to caster when taxiing. You control those with brakes-only at  slower speed and rudder at high speed. The VAST majority of tailwheel aircraft have steerable tailwheels with a breakout cam device that allows it to caster when you want to spin in a circle.

@jonhk, do you have something like document or picture describing how it work?

You steer a single engine conventional gear airplane the same as you would a twin - differential braking and rudder pressure.  Some tail draggers have bungee links between the rudder and the tail wheel providing limited steering.  But for the most part conventional gear airplanes use a free castering tailwheel.

As a millennial, I've always found it a weird convention that the term "conventional landing gear" is still used refer to a configuration that hasn't been the normal configuration for landing gear in at least twice the length of my lifetime.

Depends on the airplanes you fly.  It’s still the norm for bush and aerobatic aircraft.

@reirab - not just millennials find that odd. Someone asked a question about that around here a while back

@CarloFelicione Yeah, I know that it's still the norm for a few segments of the market, but it's hardly what I'd consider 'conventional' these days.

Remember that tricycle landing gear didn’t come onto the scene until about the mid 1940s - 30 or so years after tailwheel gear was the norm for airplanes

Mainly differential braking is used to control direction while taxiing at low speed on the ground.  Above a certain airspeed during take off and landing ground roll the rudder is also effective.


text:
What is the name and purpose of this part on the flap at the DA40?
There is a part on DA40's and also DA42's flap. I cannot find the technical document and I couldn't decide what is the purpose of that part. Is it a mass balance part or what? You may see the part at picture. (Note: First picture is not showing the part I meant to ask. The picture was wrong but I keep the picture not to make comments meaningless about it. Correct part is marked at second picture.)

Edit:
Sorry everybody, I drew wrong part before by mistake. The part marked at first picture is the aileron control rod. All previous answers and comments are correct for aileron. I add a new picture for the correct part and I found out it functions as a mass balance horn. We see housings from pictures but the related part is inside the housing.
Edit time: 11th Nov, 2016 10:30 UTC

This picture or this other one have more favorable perspectives. This looks like this when the flaps are extended. Very similar, but more obvious, on the Cirrus SR20.

Given the position on the wing, that appears to be the linkage for the aileron control rod which actuates the ailerons, not flaps.  The outboard flap hinge can be seen to the left of that.
With the new edit, yes, that points to the aerodynamic fairing for the outboard flap hinge.

From the picture links I posted under the question, you seem to be right, the nearby flap linkage fairing has a more vertical edge. But the perspective is deceptive.

Your answer is correct for my wrong marked part so I accept this as the correct answer. I have edited the question and found out the correct part functions as a mass balance horn. Thanks!

These are hinges, pivot points for the flaps, and some of them also probably contain the extension mechanism. The flaps on the DA-40 are slotted flaps, which are similar to plain and split flaps in that they typically pivot on hinges. In the case of slotted flaps the pivot points are below the wing creating a gap, or slot, between the wing and the flap when extended. These mechanisms are covered by a lightweight fairing which allows air to pass by cleanly, reducing drag.
You don't see these on airplanes with fowler flaps, where the flap is extended out the back of the wing rather than swung down on a hinge. This is a more complex type of flap, but is typically more effective than other flap types.

The comparison with other types is wrong. Plain and split flaps rotate around hinge in the wing and don't have these (there is nothing below the wing of c172 (simple flaps) or dc-3 (split flaps)). On the other hand Fowler flaps and their double-slotted variants do have flap tracks below the wing. They are even more complicated than hinge, but they are below the wing, and in jet aircraft, they are usually covered with very conspicuous fairings that double as anti-shock bodies!

You are right about the single and split flaps, that didn't come out well and I've edited. However, the c172 does not have simple flaps, they are a type of fowler flap.

It is an actuator fairing. It covers the flap actuator so to minimize the drag created by it.
An actuator directly exposed to the airflow would create more drag, increasing fuel consumption and reducing the flight range.

No the flap actuator linkage is located in the wing root on a DA-40.


text:
Airport location identification from 1960s photo?
Can anyone identify the airport location in this photo?
It would have been taken in late 1962 or early 1963 just before this DC-8 N9609Z took on its Canadian registration CF-TJL in April 1963.
There is some speculation that it is Long Beach airport or Miami airport. I think it is neither, due to the lack of palm trees, and because of what appears to be snow visible in the photo.
The sign in the background says “Home of Coppertone” which leads me to believe it might be Newark, New Jersey since Wippany, New Jersey is the head office for Coppertone.
I believe this is the first DC-8F "Jet Trader" convertible freighter. There is a sign on a tripod near the front entrance which may mean it is part of some public display.

Alex McPhee photo collection

I agree, that's snow.  Seems to be a mix of evergreens and hardwoods on the horizon.  That building with the globe on top might be distinctive enough though whether it's a newspaper or a radar I can't tell.

Do snowy places sell a lot of Coppertone? Versus sandy places?

Coppertone headquarters suggests Whippany NJ, which suggests KMMU in Morristown NJ.

KMMU is a municipal airport and the runways are too short for a DC-8.

Is that a roller coaster on the horizon at the right? Are any of the other signs legible in the original photo?

Why can't the plane be in Canada? If that's the case, Coppertone may have been based in Montreal (this information must be checked), but the thin line in the background is unlikely to be a rollercoaster: Montreal had its own amusement park only in 1967, after the expo.

The layout seen in the picture does not match anyting with 1960's Newark. There was no apron next to a road with buildings on the other side as in the pic.

Coppertone's Canada headquarters is indeed in Montreal near Trudeau airport, at least today. But this doesn't really look like Montreal, then or now. And the building looks more like a factory than an office anyway.

Based on a record of the airports where Trans-Canada Airlines operated, the US choices are: Boston, Massachusetts; New York City, New York; Chicago, Illinois; Cleveland, Ohio; Tampa, Florida and Detroit (Windsor). (TCA also operated to many other destinations in Canada, the Caribbean and Europe).

What makes this detective work extremely difficult, is that even though the time frame is really limited (acft re-registration), airports and their surroundings rarely survive without massive changes for more than a decade.  The area we see in the picture may now be covered by a new terminal, runway, parking lot etc...

I was thinking the "roller coaster" in the background could have been Six Flags/Great Adventure in Jackson Twp, NJ. Unfortunately, GA didn't open until 1974 and it's nearly 50 miles away as the crow flies, so that's right out. It does seem that "Coppertone manufacturing locations 1962" might be a fruitful search.

It looks like there is snow behind the plane, so not in Florida, at least not Miami. I guess this is a scan, do you have a better resolution  to see car plates or inscriptions on other buildings on the left side?

Hmm. That could be Burke Lakefront Airport in Cleveland OH.

That's not snow -- it's sand. That's Miami. Australian pines in the background, palm trees in the background, Coppertone signs, and the completely board flat landscape. I grew up in Miami and recognized it instantly.

@CareyGregory -- What are we seeing in the foreground, in front of the engine nacelles-- are those not tire tracks in a thin layer of snow or slush?  Or has sand gotten blown onto the pavement?

@quietflyer Must be sand because snow very rarely falls where palm trees grow. Look at the right side of the photo above the tail. See the big Coppertone sign in the background? Just to the right of that sign are two palm trees. In fact, using google maps I can pretty much pinpoint that aircraft's location.

@CareyGregory -- re "Just to the right of that sign are two palm trees."-- I believe you are right; no one else spotted those.  Write up your answer and collect your bonus--

You are very close but I'm not sure about the exact spot-- there is the shadow of what appears to be a building behind the camera-- but basically I think you've got it nailed--

The airport is Miami International. I base this on the following factors:

Personal familiarity: I lived in Miami from 1959 until 1974 and have been to MIA many times. I recognized that view the moment I saw the photo.

The white sandy soil that many mistook for snow. It is ubiquitous in
south Florida and any bare ground you see is likely to be bright
white, as seen in the dirt road behind the aircraft. Some light sand
is also blown across the tarmac, which some people also mistook for
snow.

Palm trees: Just to the right of the large, elevated Coppertone sign there are unmistakably two palm trees.

Australian pines: The horizon is dotted with Australian pines, which are extremely common in south Florida. (Or were in 1963. I believe a disease wiped out many of them in the 1970s.)

The Coppertone billboards: You couldn't swing a dead cat in Miami in the 1960s without hitting one of those signs, particularly near the airport.

The distant background: MIA is west of downtown Miami, so this photo is looking east (slightly ENE). You can see downtown Miami in the center of the photo, and the hotels of Miami Beach more distant farther to the right. Both are correctly placed relative to the airport.

The terrain: South Florida is an ancient reef, so it's utterly board flat. There is literally no such thing as a hill in Miami unless it's man-made, and the terrain in this photo fits precisely.**

The Shell gas station: As you can see in the Google Maps satellite view, there is a Shell gas station on the corner of NW 25th St. That location was a Shell gas station in 1963 as well.

I would estimate that the plane is parked approximately here, though it may be closer to the large building as pointed out in comments.

Well done - that is an awesome answer & research!

Thanks for the great answer.


text:
What are these criss-cross patterns close to Cambridge Airport (UK)?
To the immediate south of the runway at Cambridge airport, there are a large number of possibly-concrete things embedded in the grass.
I'm not sure whether they are have any aviation-related function, but they are mostly either parallel or perpendicular to the runway.
The question is - what are they?
Aerial view here.

Alien homing beacons.

Jumbo game of battleships.

In 2017 there was a major archeological dig in the area of Hatherdene Close and Coldhams Lane at the south end of the Cambridge airport.  The "criss-cross patterns" are additional exploratory trenches as part of a "Preliminary Archaeological Investigation".
Welcome
to the public consultation on the emerging development proposals for the creation of a new
neighbourhood at Land North of Cherry Hinton

Anglo-Saxon artefacts unearthed on Cambridge building site

The area is also the subject of a Planning Document. I had a quick read through the document and I found a reference to "Preliminary Archaeological Investigations", which are the trenches seen in the aerial photo.
LAND NORTH OF CHERRY HINTON Planning Document

Huh.  Seems awfully close to an airport for a residential zone.  Not sure how active that runway is, but I don't think I'd want to live there...

@DarrelHoffman Pretty common over here! We don't have much space. That airport isn't going to be servicing any large passenger jets though.

@DarrelHoffman What do you consider "awfully close"? There are airports that look just as close and apparently far busier (according to a quick look at FlightRadar24) in the northeastern US. I've got a friend that lives right under the final approach area, and he doesn't notice a thing.

@LightnessRaceswithMonica Cambridge does actually see a number of large aircraft. It's the base for Marshall Aerospace who do a lot of work on the RAF's tanker and transport fleets, so A330MRTTs and C130s are routine, plus occasional jobs for airlines. Until the TriStars were retired there always used to be one or two of those lined up on the apron.

On the other hand, the airport is expected to close altogether and be redeveloped for housing in the next decade, with Marshalls moving away; https://www.bbc.co.uk/news/uk-england-cambridgeshire-48269651

Not my video, but showing a good selection of the odd things I see coming in: https://www.youtube.com/watch?v=CBWkNE6QbCY


text:
Are engine casings expected to contain turbofan blade fragments?
On Southwest 1380, initial indications are that a fragment of the engine blade pierced the engine casing, which then hit the airplane window (or perhaps a part of the casing did). According to the BBC,

Mr Sumwalt also said a casing on the engine was meant to contain any parts that come loose but, due to the speed at impact, the metal was able to penetrate the shell.

Is this an reasonably expected containment failure?  Or is the failure to contain surprising to industry experts?

Yes, the engine casing is designed to contain the inner components if they fail. Why it didn't in this case is what the NTSB is actively investigating and nobody here can yet answer, so this question should be closed until the investigation is completed.

Ben's comment is basically the answer. “Yes, you're right to be confused/disturbed.” The BBC line makes it sound as if the event were fully understood.

Note that there was already similar accident, Southwest B737 near Pensacola on Aug 27th 2016, uncontained engine failure, but that investigation is also still in progress and nobody seems to have much idea why in the inlet cowling separated. Just that in both cases the initial failure triggered failure of the inlet cowling ahead of the fan and that in turn caused all the other damage.

We don't yet know how or why the engine casing failed to contain the fan blade on Southwest 1380.
But yes: Not only are the engines designed to contain blade failures at fan red-line speeds, but they are also required by 14 CFR 33.94 to confirm they do, typically via destructive "blade-off testing."
(There are a number of good videos of this testing online: Search "turbine blade fail test" or "blade-out engine test.")
As noted here "fan blade-out" failures in the real world are virtually unseen.  (Turbine blade failures are relatively common and can even go unnoticed until major service teardowns.)

I should be noted that uncontained engine failures still do occur at rate of several a year. Quick search shows at least 5 in 2017 and it's similar for preceding years. Usually this is because a larger fragment breaks loose—the requirement is to contain a single blade only.


text:
What is ground effect?
We've all heard the "acts like a cushion of air" explanation tossed casually around by CFIs.
There's also plenty of books and reference materials that give a detailed, accurate, and complete explanation of ground effect, and which are incomprehensible to most student pilots.
What's the simplest way to accurately explain ground effect?

https://en.wikipedia.org/wiki/Ground_effect_%28aircraft%29 ? If fear the judging of the superlative "simplest" will be opinion-based.

@yankeekilo - That link is exactly the kind of explanation I'm not looking for. Not only is it written with as much technical language as possible, it skips steps in the explanation.

O.k. - I am looking forward to answers, Getting rid of all the technical terms comes with the risk of oversimplification.

I'm disappointed in most of these answers because the correct ones are too complex, and the simple ones have been down voted probably because they're too simplistic.

The "cushion of air" comparison is actually pretty accurate. Phillipe's explanation is more specific but it's really nothing more than how or why you get that cushion of air between the wings and ground.

I don't know what the wikipedia article looked like at the time of this post but the current version on April 29, 2017 actually doesn't seem all that bad. I know nothing about any of this and it makes sense to me (although I may have been "primed" by reading the answers here first).

It's impossible to give a correct AND simple explanation I think. I would explain it like this if I was asked:
The downwash from the wings and the downward component of the wingtip vortices create a higher than normal pressure area below the wings because the air hits the ground and can't "escape", increasing lift.
Induced drag is reduced because wingtip vortices (causing drag) can't fully develop close to the ground.

“downwash from the wings” and “downward component of the wingtip vortices” are only one thing, not two different things!

Your second sentence suffices.

For a simple and correct answer you need first to understand induced drag.
Please read this answer if you feel unsure.
Short version: The wing creates lift by deflecting air downwards. Induced drag is the consequence of this deflecting, because the resulting force of this deflection process is tilted backwards by half the deflection angle. Due to the backward tilt, the force has a horizontal component, pointing backwards. This is induced drag.

The ground effect will prevent this flow field from developing fully, because air cannot flow into the ground. Consequently, the deflection angle is lower, and also its horizontal component, i.e. drag.
The same happens ahead of the wing, where the upward motion of air ahead of the stagnation point is also restricted. Another consequence of this is a reduced lift curve slope in ground effect.
Lift is higher relative to induced drag compared to the free-flow case because the wing somewhat blocks the outflow of air at the trailing edge, and this results in a higher pressure on the bottom of the wing compared to the free-flow case.
This "cushion-effect" explanation is actually quite correct. The pressure which lifts the airplane is not only created by accelerating air downwards, but also by ram pressure. This effect disappears once the wing is far enough from the ground.

Here's my simplification, it's not the full story, but it covers the essentials.
Lift:
When you are in free space, the high pressure below your wing dissipates into the surrounding air. When you're in ground effect, the high pressure below the wing encounters an incompressible solid, and therefore cannot dissipate as quick, causing higher pressure below the wing, and therefore more lift.
Drag:
When you're in free space, the wake (turbulent, low pressure) behind your aircraft dissipates unimpeded until it becomes uniform with the surrounding atmosphere. When you're in ground effect, the air near the ground absorbs this dissipation  quicker because it has to shear against the ground (more friction that air in free space). Additionally, wing-tip vortices encounter the ground and dissipate much quicker than in free space.
I suspect the reason GE is tied to wing length is because the longer your wing is, the stronger your wing tip vortices, and the further air has to travel laterally to exit the high pressure zone under the wing.

The ground acts as an aerodynamic mirror. When the wing approaches the surface it is as if an inverted wing comes from below. Their high pressure areas amplify each other, increasing the efficiency and thereby reducing the drag.

Technical terms:  ground effect produces an "image force."   This image-force provides 100% of the lift ...as long as the wing altitude is far smaller than one wingspan.  Also, ground effect is a three-dimensional effect involving wingspan and vortex-shedding, therefore a typical airfoil diagram (airfoil section with flow-lines) cannot explain it.

Simple explanation:
When out of ground effect, air on the bottom of the wing has plenty of room to move around. When in ground effect, the air on the bottom of the wing can't move around nearly as well and therefore pushes the plane upward to try and make more room.

How does that reduce induced drag?

You asked for simplified.

in normal flight high above the ground, wings create lift by deflecting an air stream downwards. This is not possible close to the ground: air does not travel through the ground surface.
Picture the downward air stream being bounced back and increasing pressure underneath the wing. This happens partially at the wing, not only behind it, because at sub-sonic speeds the air is being split in front of the wing.
So in ground effect, lift is created by pushing air downwards and by increased static pressure underneath the wing, like a hovercraft. And the increased pressure does not come with an induced drag penalty. And that is the main difference: total drag is lower in ground effect than in normal flight.

What happens behind the trailing edge is surely irrelevant.
The wing has an angle of incidence to the ground so there is a wedge effect under it, presumably increasing pressure under the forward part of the chord and less so under the after part due to venturi effects.
Looks like a cushion effect to me and the airflow over the wing is deflected, and pressure reduced, as it would be at altitude.

The wing pushes air down.
In flight, that air pushes on other air that moves.
In ground effect, that air pushes on the ground that doesnt move.
Pushing things that move is more difficult than pushing things that dont move. Like walking on sand vs walking on pavement.

Take a look at Pelicans in flight and you can see "ground effect" hard at work! Not complicated and most readily observed over water and not Terra Firma. For great YouTube videos simply Google "ground effect vehicle" and in particular the fantastical creation by the USSR during the Cold War (1948-1989). "Ground effect" is lift...and indeed forward velocity...gained when "sailing" just above a preferably watery surface. In nautical terms it's known as "displacement"(as opposed to Buoyancy) but you are in fact displacing the air just above the water instead of being on or in that physical surface. Their are many finite and interesting realities that exist in this "space" as well.

You should add the link t the video you mention. Moreover, you may emphasize what your answer adds to existing one.

Near the ground, the ground can push up on the airplane, giving it more lift.

I thought that reduced drag was the main factor in ground effect, which causes increased lift?

There's no difference. Increased lift for same drag is the same as reduced drag for the same lift.

@DavidSchwartz No it's not the same. Suppose you go to the market with $5. If you accept the first stall's offer of a dozen apples for $5, you go home with 12 apples and no money. If you accept the second stall's offer of a dozen apples for $4, you go home with 12 apples and $1 in change. If you accept the third stall's offer of 15 apples for $5, you go home with 15 apples and no money. The second and third stalls are giving you the same lift/drag ratio but are behaving noticeably differently.

@DavidRicherby: David is on to something here, even if he does not explain it. In the end, the ground supports all aircraft aloft, but in case of the wing in ground effect this support is more focused.

@DavidRicherby Your analogy shows why your argument is incorrect. In your analogy, there's no ability to choose the total taken. But a pilot can choose the total amount of lift+drag to take by moving the stick forwards and backwards.


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If both propellers and wings are airfoils, then why do propellers deflect air perpendicularly to the rotor, but wings not?
Here is my dilemma.  I have seen a lot of videos of airfoils in wind tunnels, and I've noticed how the airflow always moves away from the trailing edge parallel to the wing, or at a very small angle away from the wing as in this video:

I've also heard that propellers are nothing more than rotating wings (airfoils), producing lift sideways as opposed to upwards.  What confuses me is that in the case of the propeller, the airflow leaves the propeller at a much higher angle, and not straight as is with the wing.  In other words, the airflow is deflected backwards from the prop.  I just can't understand how the wing and propeller, which are two very similar shapes (maybe not that similar, but they operate by the same principle), deflect air in two radically different directions.
I have a few thoughts on why this happens, but I think it's better if someone tells my first.

https://aviation.stackexchange.com/a/44886/4108 The image in this answer may answer your question: the angle is actually really shallow for propellers too, they just rotate really fast.

On a stationary aircraft the propeller keeps beating the air at the same spot. That generates a horizontal column of air. If you took wings lifted them more than 100 feet off the ground and kept beating the same spot you'd also get a column of air moving. Actually that precisely describes what a helicopter does. A helicopter has "wings" oriented horizontally and rotating fast. It also has a tail rotor (wings) oriented vertically.
A wing does push air down but it doesn't generate a column of air moving simply because it always keeps moving on to a different air mass. Same thing with a propeller moving fast forward. It doesn't actually move the air backwards very much. It also moves on to new air.

Don't let wind tunnels fool with your perception of reality. In the real world, it's the wing that moves while the air remains stationary.
Consider a video just like the one you posted, but filmed with a stationary camera. (The one in your video is attached to the wing and moves along with it.) You'd see the folowing scenes:

The field of view is filled with stationary air.
A wing quickly passes through the video from right to left.
The air now moves downward more or less vertically.

Expanding on @RainerP's answer, look more carefully at the wind tunnel footage.  The smoke streams are slightly lower behind the wing than they are in front of it.  This may look insignificant, but it isn't: the air in the tunnel is moving extremely quickly, and therefore only has a very short length of time to move vertically after it has left the wing before it is carried off camera by its horizontal motion... if we can see a 3m section of tunnel and the air is moving at 200mph, then it stays on camera for only around 30ms.  So if the air coming off the wing gains a vertical velocity of, say, 3 meters per second, you'd only expect to see a deflection of around 10cm by the time it reaches the edge of the frame.

The airflow behind an aerofoil (sorry, I'm English, I can't bring myself to write 'airfoil'!) always moves downwards away from the trailing edge, if the aerofoil is generating lift. This is Newton's Third Law in action: every action has an equal and opposite reaction.  It is not possible for the air to act on the aerofoil to generate lift without the aerofoil acting on the air to accelerate it downwards.
From Newton's Second Law, the force required to accelerate something is proportional to the mass of the thing and the amount by which it's accelerated ($F=m\times a$), so to generate the same amount of reaction force you can accelerate a small amount of air a lot, or a large amount of air a bit.  In a continuous process this force is also equal to the mass flow of the thing being accelerated (the mass per unit time) multiplied by its ultimate change in velocity.
Wings are typically bigger than propeller blades, so the mass flow of air past them is higher for the same airspeed, and the required change in velocity is therefore lower for a given amount of lift.
(Side note: it might appear that propeller blades have a much higher airspeed than wings, but in flight they really don't.  The tips are almost always subsonic, and the linear speed of the blade decreases towards the hub too, so the speeds involved are loosely comparable to those of a wing.)

It sounds like you might be confusing the direction of airflow vs. the direction of lift:  As either a wing or a propeller moves through the air, the flow is approximately parallel to the airfoil.  In both cases, the air at the trailing edge of the airfoil is moving "downward" (relative to the airfoil) to some extent.  This is what produces lift (on a wing) and thrust (on a propeller), both of which are approximately perpendicular to the airfoil.  For a given air-relative speed and airfoil shape, both a wing and a propeller will deflect the airflow the same amount:  A propeller does not deflect the air perpendcular to the rotor, it provides thrust in that direction.
As an airplane moves through the air, its wings (hopefully) hold it the same distance off the ground.  As a propeller (on a moving airplane) moves through the air, the path it follows looks much like a screw, with each pass of the propeller being roughly the same distance from the previous path.


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How do airplane balance tabs (or control tabs) change the force on the pilot's controls?
According to the PHAK ch. 6 and this description regarding Ameristar 9363, one type of tab on an elevator is supposed to "decrease the pressure the pilot needs to exert on the flight controls." This is the tab I'm asking about.

Where does the force go – does the plane get the same amount of pitch control with or without this tab?
When its purpose is to reduce the pilot's exertion, how does the use of this tab differ from making the whole elevator smaller?

In researching this question, I found a lot of different names for these tabs, so feel free to clear that up as well.

A tab is like an additional, miniature control surface, with its own change in lift. Since it sits near the trailing edge of a larger control surface, this lift change affects the hinge moment of the larger surface.
There are several types of tabs:

The simplest is a strip of metal which can be bent on the ground so it changes the deflection angle at which the control surface has zero moment.

Next on the list is a tab with can be set by the pilot, but its angle relative to the control surface does not change with the deflection of the latter. In both cases, the effectiveness of the control surface is unchanged.

More complex tabs do change their angle with control surface deflection. Flettner or servo tabs move opposite to the deflection of the main control surface and greatly reduce the hinge moment, at the cost of a small reduction in control power (think 90% force reduction for a loss of 20% in control power). On small airplanes you might even find tabs which increase the control force by being geared in the opposite way.

Flettner tab (picture source)

But it gets even more interesting with spring tabs: Here the gearing changes with tab hinge moment, so at high dynamic pressure the gearing is higher and control forces do not grow with the square of speed any more. Of course, more force reduction means less control power, but without such a device the control forces would be too high for effective control.

Spring tab, picture from this answer.

Spring tabs need careful design: Their feedback might cause flutter at specific speeds. Also, the reduction of control power from tab deflection can be as high as two thirds of the control power of the original control surface, but they could reduce the control forces down to 4% or even 2%. They were the last resort before the introduction of hydraulic controls to make large, fast airplanes controllable at high speed. Due to their high effectiveness, they require high precision in manufacturing and careful adjustment in flight testing. The Junkers Ju-88 used a combination of tabs, overhanging balance and adjustable hinge position for very light aileron forces even at 500 km/h, but each airplane required several flight hours of testing and adjustment before delivery.

how does the use of this tab differ from making the whole elevator smaller?

A size reduction will reduce control power and forces in equal measure while a well-designed tab will cost between 10% and 70% in effectivity for a force reduction of up to 98%.

Thanks for answering all parts of my question! The flettner/servo tab was what I had in mind when asking. I'm familiar with the systems on Pipers and Cessnas. One follow-up: Why is it hard to find examples of aircraft whose servo tabs but not the main control surface are linked to the flight controls? It seems like a good idea, but of course I'm no expert...

The NASA article explaining the spring tab also mentions the whirleron(!), a normally windmilling small prop aft of the wing, whose blade angle is set by the pilot.  Then its spinning applies force to the aileron.  Wow.

@Edb240 Large airplanes used to have directly linked servo tabs before hydraulic controls were common. Examples are the Do-X where the servo tabs were above the control surfaces or the Bristol Britannia. This is prone to flutter, however, so faster jets quickly moved to hydraulic actuation.

"Why is it hard to find examples of aircraft whose servo tabs but not the main control surface are linked to the flight controls?" - All [McDonnell] Douglas aircraft from the DC-4 through DC-9 (except the MD-90) are examples of such, so I wouldn't exactly call examples of such "hard to find"...

Ok, good to know. I only meant "hard to find" in the sense that most articles don't mention specific aircraft – they just explain the concept in the most general of terms – which is why I asked on this site. Thanks

PHAK chapter 6 shows a trim tab, and the linked discussion about Ameristar describes a servo tab. From this answer:

The servo tab is an aerodynamic lever, it is connected directly to the pilot flying controls.
The trim tab has a constant angle relative to the control surface.

The trim tab is the easy one: it changes only the offset force required to keep the aircraft in trim. Instead of aerodynamics pushing the control one way and the pilot balancing by pulling the other way, the trim tab is positioned so that at trimmed flight there is no aerodynamic force attempting to pull the control surface away.

The control tab (also called servo tab or Flettner tab) is for reducing aerodynamic feedback forces, while not reducing elevator surface area. The aeroplane requires a minimum elevator surface area for control in all circumstances. Where does the force go - same as with any lever, reduce forces by increasing moment arm.

The tab you’re talking about is more commonly known as a “trim tab”. I encourage you to go through your preflight checklist where you’ll explicitly check whether the elevator trim tab is secure (for a Cessna at least).
It’s literally a tab on trailing edge of the elevator. The tab can be extended forward and backward, effectively changing the total downforce of the elevator. The change in downforce changes the amount of force the pilot has to provide on the yoke (extending the tab downward (trim up) increases the downforce and thereby requires less backpressure on the yoke).
Some other planes (eg Cirrus) don’t have such tabs. Instead, the trim is changed digitally and affects the force of servo motors that are attached to the elevator/rudder controls (the same motors that control the auto pilot). The extra force provided by these motors effectively changes the force the pilot has to input.


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What were the procedures to follow in US Airways Flight 1549 during descent?
In the documentaries, and in the texts about the US Airways Flight 1549 ("The Miracle on Hudson"), procedures and checklists are mentioned and shown as a good example.
What procedures were they following in that case, and what could have gone wrong if they were not followed?

As far as "what were they": What should a pilot do to perform a successful emergency water landing?

17 seconds after bird impact, they used the "QRH Engine Dual Failure checklist" as per the NTSB report at:
https://www.ntsb.gov/investigations/AccidentReports/Reports/AAR1003.pdf

Even though the engines did not experience a total loss of thrust, the
  Engine Dual Failure checklist was the most applicable checklist contained in the US Airways QRH, which was developed in accordance with the Airbus QRH, to address the accident event because it was the only checklist that contained guidance to follow if an engine restart was not possible and if a forced landing or ditching was anticipated (starting from 3,000 feet). However, according to postaccident interviews and CVR data, the flight crew did not complete the Engine Dual Failure checklist, which had 3 parts and was 3 pages long. Although the flight crewmembers were able to complete most of part 1 of the checklist, they were not able to start parts 2 and 3 of the checklist because of the airplane’s low altitude and the limited time available.

The "procedure" that the captain followed was the mantra taught to student pilots very early in their training: aviate, navigate, communicate. The ultimate priority in all flight circumstances is to first fly the aircraft. By realizing that 1) continued flight was impossible, 2) attempting to restart the engines was futile, and 3) deviating to the softest and least congested improvised landing site was necessary, in fact in these circumstances the best possible option, the captain saved his own life and the lives of his crew and passengers.
The captain was almost a 20,000 hour pilot at the time of that accident and the first officer had accumulated over 15,000 hours of pilot time. This cannot be understated. This was an extremely experienced flight crew.
In many years of dealing with imminently life-or-death circumstances, I have seen two categories of people: those who act and those who freeze. Obviously, the crew in this situation was composed of people in the former category. That is the category in which I place myself, but thus far almost all of the life-or-death circumstances I have faced have been ones I have trained heavily to mitigate. My actions have been almost reflexive based upon that training, but in my craft I am also well over the 10,000 hour mark.
The ultimate answer to your underlying question of how did this flight end successfully is the right kind of experience of the flight crew, and this cannot be summarized in a checklist or procedure. They knew how to fly. They intimately knew the systems of their aircraft. Most importantly, they worked together as a team to accomplish the mission even though that mission had changed significantly since the time when they were cleared for takeoff.

"Most importantly, they worked together as a team" – They were indeed well-trained in Crew Resource Management, which is widely heralded as a major reason for the positive outcome of this incident. In fact, Captain Sullenberger introduced CRM at his former employer and developed CRM procedures and CRM training.


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How do pilots set the exact amount of thrust needed for a reduced power takeoff?
I know jet-powered airplanes very rarely use 100% available power for takeoff, and most often reduce power to increase engine life. How does a pilot set thrust to an exact level?
The airplanes I'm referring to are common commercial jets such as A320/B737 types.
If they'd set it manually with thrust levers, there are some complications: there are no placards on them. If you try setting revs via the displays, revs and temperatures do not change instantaneously, and looking at the indicators and adjusting the lever would be a dangerous distraction during take-off (imagine: the engines roaring, the brakes are applied and tires are rubbing against the asphalt; or the plane is rolling, and the pilot is looking at the gauges).
On the other hand, if a limit is set via FMS, how does it know when to add more power if it's urgently needed?

Most aircraft have a 'TO/GA' (Take Off/Go Around) button on the throttles, which overrides any autothrottle limits and delivers maximum thrust.

@SomeoneSomewhere, Boeings have a button. On Airbus, moving the thrust levers all the way forward works that way.

Just as a matter of historical info, in 747-100/200 aircraft it was the flight engineer who, when the call was given by the flying pilot, set the takeoff power to the appropriate N1 with the thrust levers. A really smooth f.e. could do it without any jockeying of the thrust levers. If more power was urgently needed, max power would be called and the f.e. would set that.

The EMB-145 used a combination of FADEC settings and the thrust levers to select the desired thrust and to signify the need for additional thrust.
The thrust levers had a detent that selected "100%" thrust for the given mode the FADEC is operating in.  If you pushed the thrust levers past the detent to "max" this would give you extra thrust.  The mode the FADEC is operating in is selected by a button in the cockpit that cycles through the available modes.
For takeoff power the modes were "ALT T/O", "T/O" and "E-T/O" which gave you 90%, 100% and 107% thrust for takeoff when the thrust levers were in the detent.  If advanced past the detent this would put the mode into a reserve mode and depending on model would give you up to 110% or 117% thrust.
Setting the exact amount of thrust needed was up to the engine FADEC units, our job was just to tell it what thrust mode it was in and it scaled the output of the thrust levels to that mode.  Flying a 90% thrust takeoff, a normal rated climb and then reducing to cruise levels only required initially setting the thrust levers into the detent and adjusting the FADEC mode.

I think this most accurately answers the question of "how do the pilots set the thrust?": select a mode, move the levers to the detent, let the computer do the rest.

caseys answer nicely describes the procedure for the Embraer 145. Since you specifically mentioned the Boeing 737 and Airbus A320, here is how it works for these aircraft:
Boeing 737
All Boeing aircraft have autothrottles with servo motors which move the thrust levers in the cockpit. This system is also used to set takeoff thrust:

During the preflight, the desired derating is selected in the CDU (see left image below).
When starting the takeoff roll, the thrust levers are advanced to about 40% N1.
After the engines are stabilized, the TOGA button on the thrust lever (see right images below) is pressed and the autothrottle becomes active. The servo motors then move the thrust levers to the desired position.

Airbus A320
Airbus aircraft do not move the thrust levers with autothrottle engaged. The thrust levers usually remain in the CL (climb) detent during flight and the autothrottle sets the desired thrust directly.
The takoff procedure starts similar to the 737, until the engines have stabilized. Then, the thrust levers are moved into the FLX/MCT (flex/max. continous) detent (see image below). This will set the derated thrust. For maximum takeoff thrust, the thrust levers can be placed into the TOGA detent.

Usually power output for a jet engine is gauged from its low pressure turbine speed.  In turbofans, this corresponds to the fan speed, displayed as N1.  In general, the derated takeoff thrust will be selected based on performance calculations done prior to flight, taking into account weight, runway available, climb performance and ambient atmospherics, which will determine the appropriate N1 speed to set during the takeoff roll.
There exist two types of derated thrust operations: fixed and variable.  Fixed derate is a pre-set derated thrust by the engine OEM.  Variable derate offers the flight crew the ability to select the derated thrust from a range of values.
For more information, consult AC 25-13 on this.
So also is this presentation from Boeing, which includes how thes factor are loaded into to the FMS, which then computes a corresponding N1 value and displays this on EICAS, as does this presentation for Airbus.

I don't think this quite answers the question. He's not asking how the derated thrust target is identified, he's asking how exactly it is selected on takeoff. Do the pilots just keep advancing the throttles until N1 reaches the desired amount? You should incorporate Simon's comment in your answer to make it complete, in my view.

Interesting description of the principles. If you keep this good material and just add in introduction that the thrust levers are just in the TO/GA position regardless of the actual thrust that will be delivered by the engines (if this is the case), then this will be a good answer (as @Ben commented).

@mins, on Airbus, they are not in the TO/GA position. TO/GA on Airbus always means maximum possible thrust. There is another detent, labelled MCT/FLX, that selects the derated thrust. On some models, the CLB detent can also be configured for derated climb. Above the CLB detent, the levers are never placed in arbitrary position, only in one of the detents.

@JanHudec You should add a link such as this one to your comment